For the production of the finest structures in electrotechnical and/or micromechanical components on the nanometer scale, it is desirable for light or generally electromagnetic radiation of ever decreasing wavelengths be used for the lithography method underlying the manufacturing process. Accordingly, projection exposure systems for illuminating and imaging a reticle containing the desired microstructure or nanostructure are known that employ electromagnetic radiation in the range of extreme ultraviolet light. For this technique, called EUV lithography, optical membranes are used in order that they may serve, for example, as spectral filters, as described in U.S. Pat. No. 7,154,666 B2. In addition, there are other applications in the field of EUV lithography, such as those described in U.S. Pat. No. 7,153,615, U.S. Pat. No. 6,749,968, U.S. Pat. No. 6,683,936 and U.S. Pat. No. 6,150,060. Because the application areas referred to in these documents constitute potential applications for the optical membrane element of the disclosure, the disclosure content of these publications is incorporated by reference herein in their entirety.
U.S. Pat. No. 5,068,203 furthermore discloses how, for example, a thin silicon membrane may be produced. Its disclosure content, too, is incorporated herein by reference.
The membranes usually have a very low thickness in the range of 50 to 500 nm and are desirably planar and smooth in order that they may be used in optics without causing aberrations. The extended area of the membranes can range from 0.5 mm edge length or diameter to several 100 mm edge length or diameter.